Roster slugs through Home Assistant's real slugify (P2 fix)

The per-child entity ids are derived from the child name by Home
Assistant's real slugifier, which transliterates every script through
unidecode; the hand-rolled Latin-only mirror in sensor.py dropped
non-Latin characters instead (slugging 京子 to "unknown"), so the
roster's slugs diverged from the actual entity ids and the
party-board/strategy auto-discovery silently failed for non-Latin
households.

Use homeassistant.util.slugify at runtime, composing the registry's
64-character entity-id cap the roster needs (verified against HA
2024.6: slugify itself does not truncate; the entity registry
truncates the full <domain>.<slug> id). Give the mock harness a
faithful homeassistant.util.slugify stub — python-slugify's frozen
legacy pipeline with unidecode, verified byte-for-byte against real
python-slugify across Latin, Cyrillic, CJK and Greek name shapes —
and cover the non-Latin resolution contract in tests (roster slug ==
the object id HA's entity-id derivation produces).

Feature-review finding (P2): auto-discovery slug must match Home
Assistant's real slugify.

uv.lock

@@ -385,6 +385,7 @@ dev = [
     { name = "pytest" },
     { name = "pytest-asyncio" },
     { name = "pyyaml" },
+    { name = "unidecode" },
     { name = "uvicorn" },
     { name = "voluptuous" },
 ]
@@ -400,6 +401,7 @@ dev = [
     { name = "pytest", specifier = ">=8.0.0" },
     { name = "pytest-asyncio", specifier = ">=0.24" },
     { name = "pyyaml", specifier = ">=6" },
+    { name = "unidecode", specifier = ">=1.4.0" },
     { name = "uvicorn", specifier = ">=0.30" },
     { name = "voluptuous", specifier = ">=0.14" },
 ]
@@ -689,6 +691,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/67/81/4add07e5172b7ac40d8ed5ff580409a7801a4fe26d529bdd915401dabfbe/typing_inspection-0.4.4-py3-none-any.whl", hash = "sha256:65b8397ba37ccbce054456aaccddfc91e6e3083c92824df348d96ca832f3f147", size = 14750, upload-time = "2026-08-12T12:37:24.648Z" },
 ]
 
+[[package]]
+name = "unidecode"
+version = "1.4.0"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/94/7d/a8a765761bbc0c836e397a2e48d498305a865b70a8600fd7a942e85dcf63/Unidecode-1.4.0.tar.gz", hash = "sha256:ce35985008338b676573023acc382d62c264f307c8f7963733405add37ea2b23", size = 200149, upload-time = "2025-04-24T08:45:03.798Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/8f/b7/559f59d57d18b44c6d1250d2eeaa676e028b9c527431f5d0736478a73ba1/Unidecode-1.4.0-py3-none-any.whl", hash = "sha256:c3c7606c27503ad8d501270406e345ddb480a7b5f38827eafe4fa82a137f0021", size = 235837, upload-time = "2025-04-24T08:45:01.609Z" },
+]
+
 [[package]]
 name = "uvicorn"
 version = "0.53.0"